Clutch control mechanism



Feb. 17, 1942 LEUKHARDT 2,273,277

CLUTCH ,CONTROL MECHANISM Filed July 12, 1938 2 Sheets-sheaf 1 at I i8 13 e M n :3 EN

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2 Sheet-Sheet 2 A. R. LEUKHARDT CLUTCH CONTROL MECHANISM Filed July 12, 1958 Feb. 17, 1942 INVENTOR! Arllpur RLeu/dlzardi.

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Patented Feb. 17, 1942 v CLUTCH CONTROL MECHANISM Arthur R. Leukhardt, New York, N. Y., assignor to Bendix-Westinghouse Automotive Air Brake Company, Pittsburgh, Pa., a corporation of Delaware Application my 12, 1938, Serial No. 218,843

9 Claims. (Cl. lea-3.5)

This invention relates to motor vehicle clutch controlling mechanism and more particularly to a control device for coordinately controlling the operation of such a mechanism with other vehicle controls, such as the gear shifting apparatus and/or the accelerator pedal.

In one type of clutch operating mechanism heretofore provided, the vehicle clutch has been controlled by the operation of a suitable power device, and the energization of the latter has been determined by the speed of the vehicle engine.

More particularly, in such prior installations, in-

crease in engine speed above a predetermined idling speed has determined the rate of deenergization of the clutch controlling power device and hence the rate of clutch engagement. In

adapting such devices to vehicles now in use, several problems have been presented. Among these is the variation in force required to complete disengagement of the clutch. For example, in certain installations, ithas been found that a force in excess of two hundred pounds has been necessary to effect a disengagement of the relatively movable members of the clutch. Approximately two hundred pounds of this force has been required to overcome the mechanical friction inherent in the clutch. Hence, in permitting engagement of such a clutch, the disengaging force must be reduced two hundred pounds before the clutch begins to engage through the action of the usual return springs associated therewith. In devices of the character under discussion, the engagement of the clutch has been rather sudden after the disengaging force has been reduced by the amount indicated above.

It is accordingly one of the objects ofthe present invention to provide a clutch controlling mechanism which shall be operable to efficiently disengage the clutch and permit a graduated and smooth reengagement thereof.

Another object is to provide a combined gear shift and clutch controlling mechanism, so constituted as to provide automatic clutch operation during shifting of gears, such clutch operation insuring complete clutch disengagement between shifts and enabling graduated engagement in accordance with increase in engine speed.

Another object is to provide a novel arrangement for controlling the operation of a power device for a vehicle cl tch. such arrangement securing a finely graduated control of the power device during increase in the engine speed above a predetermined idling speed, whereby the clutch engagement may be smoothly effected.

Still another object .is to provide a novel arrangement for securing graduated clutch engagement in accordance with increase in engine speed and wherein the initiation of the engagement of the clutch may be controlled by operation of the accelerator pedal.

A further object is to utilize, in a controlling apparatus of the above character, a slight movement of the engine accelerator or other vehicle controlling member for quickly reducing the'degree of energization of the clutch operating power device to the point where initial engagement occurs and to thereafter graduate the further deenergization of the device inaccQrdance with increase in engine speed.

A still further object is to provide a novel and relatively simple mechanism for securing the above mentioned desirable results and advantages, and one which is so constructed and arranged as to be capable of ready adaptability to vehicles now in use.

Other objects and novel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawings, wherein two forms of the invention are illustrated. It is to be expressly understood, however, that the drawings are utilized for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawings, wherein similar reference characters refer to like parts throughout the disclosed therein a motor vehicle clutch controlling mechanism constructed in accordance with the principles of the present invention, the same Power means are provided for causing disen gagement of the vehicle clutch and for initiating engagement thereof and, in the form shown,

. member I9 into engagement with the clutch member I2 in order to effect a driving connection between driving and driven shafts I4 and I5 respectively.

The gear shifting mechanism 6 includes a pair of primary shifter bars I5 and I1, capable of being selectively engaged and moved in opposite directions by any suitable mechanism, not shown. For example, manually operable means, such as the usual gear shift lever found in gear shifting mechanisms now in general use, may be employed for selectively engaging and moving the primary shifter bars I8 and I1. However, it is to be understood that the invention is not limited to the manual operation of these bars since any suitable means may be utilized, it being only necessary that the bars be shifted longitudinally for the purpose of establishing a desired gear relation. The primary shifter bar I6 is secured or operatively connected to a secondary shifter bar I8 in any suitable manner, not shown, so that longitudinal movement of the bar I6 will move the bar I8 in a similar direction. A secondary shifter bar I9 is likewise operatively connected to the bar I1 and moves with the latter.

The secondary shifter bars I8 and I9 are respectively operably connected to the shiftable transmission gears and the construction is such that longitudinal movement of the interconnected shifter bars I5 and I8 in opposite directions will serve to establish first and reverse gear ratios, while combined movement of the interconnected shifter bars I1 and I9 in opposite directions will serve to establish third and second gear ratios.

In order to effect automatic operation of the clutch 5 as the various gear relations in the transmission 8 are established, means are associated with the shifter bars of the transmission for coordinately controlling the energization of the fluid motor 1. As shown, such means include a pair of valve mechanisms 29 and 2I respectively associated with the shifter bars I9 and I8. Each of these valve mechanisms includes intake portions 22 and I22 and exhaust portions 23 and I23, springs 24 and I24 serving to maintain the respective valves in the positions shown when the gear shift is in neutral or in one of the gear-engaged positions. The intake valve por- Gill haust valve portions 23 and I23 are respectively housed within chambers 28 and I28, theichamber I28 communicating with the fluid motor 1 by way of conduit 29. A valve operating member 39 is provided for the valve 2|, and, as will be seen more particularly f':om Fig. 4, this operator is provided with a cam-shaped extremity ,3I adapted to be received within notches 32, 33 or 34 of the shifter bar I8. Notch 32 corresponds to the neutral position of the bar, while notches 33 and 34 respectively correspond to first and reverse gear relations. Intermediate the notches, the shifter bar I8 is provided with cam portions 35 and 38 which cooperate with the extremity 3I of member 39 to shift the same to the right, as viewed in Fig. 1, during longitudinal movement of the shifter bar. urged into engagement with the shifter bar I8 by means of spring 31, this construction permitting the valve 2I to close whenever the extremity 3I is in registry with one of the notches of the shifter bar.

The valve operating member 39, see Fig. 1, is provided with an interiorly disposed bore 38 having an exhaust valve seat 39 formed in one end, and havingv also a laterally disposed opening 49 which constantly establishes communication between the bore 38 and a duct 4I, irrespective of movement of the member 39. Duct 4I communicates with the chamber 28 of valve 29, and, from this arrangement, it will be perceived that the last named chamber is in constant communication with bore 38.

Valve 29 is provided with a valve operating member 42 constructed similarly to the valve operating member 39. As shown, the member 42 is provided with a cam-shaped extremity 43 which is adapted to be received within notches I formed in the shifter bar I9. That is, referring to Fig. 4, the extremity 43 of member 42 may be received in any one of three notches positioned along the length of shifter bar I 9 in precisely the same manner as is shown in Fig. 4 in connection with shifter bar I8. In view of this similarity of construction, it is not considered necessary to illustrate the notches 'on shifter bar I9. As in the case of shifter bar I8, when the'extremity 43 of member 42 engages the center notch, the shifter bar I9 is in neutral position. When either of the outer notches is engaged, however, the

shifter bar is in second or third gear relation.

The valve operating member 42 is provided at its opposite extremity with an exhaust valve seat 44, see Fig. 1, and is formed with an interior bore 45 having a lateral opening 46 in constant communication with a, conduit 41, this arrangement being provided for a purpose which will appear more fully hereinafter.

With the construction heretofore described, it will be readily understood that the chamber 25 is constantly supplied with a source of fluid pressure from reservoir 26 through conduit 21. Hence, movement of either of the valve operating members 39 or 42 to the right, as viewed in Fig. 1, will move the respective valves 2I or 29 to such a position as to open the intake valve portions thereof. It is to be pointed out that the arrangement of the cams on the shifter rods is such that the movement of the valve operating members occurs prior to actual engagement or disengagement of the transmission gears, either the lost motion inherent in the gear shifting mechanism being utilized for this purpose, or, if this is found insuflicient, a lost motion connection may be provided between the shifter bars I8 and I9 and the shiftable gears operated thereby.

In the event that valve 2I is moved so that the intake portion I22 thereof is opened, fluid pressure will be conducted from chamber 25 to the clutch motor 1 by way of chamber I28 and conduit 29. As soon as valve operating member 39 Member 39 is constantly opening 46 and conduit 41 in a manner which will appear more fully hereinafter.

The clutch motor 1 will be energized in a somewhat similar manner upon operation of the shifter bar I9 to effect a desired gear relation. In this instance, when the latter is moved, valve operating member 42 will be shifted to the right by reason of one of the cams on the shifter bar, and exhaust valve seat 44 will engage the exhaust valve 23 of valve 20. The latter will be moved to the right, opening the intake valve 22, thus connecting chamber 25 to the clutch motor by way of chamber 28, duct 4|, opening 49, bore 38,

chamber I28, and conduit 29. Following the establishment of the gear relation and the registry of member 42 with the proper notch of the shifter bar I9, the said member will be returned to the position shown by means of a spring 48. Thus the chamber 28, in communication with the clutch motor 1 through the connections above specifically described, will be connected to conduit 41 by way of duct 45 and opening 46. It will hence be understood that the construction heretofore described will enable synchronized energization and deenergization of the clutch motor 1 to be secured as the shifter bars l8 and 19 are moved to establish desired gear relations.

The present invention, in addition to providing means for controlling the energization of the clutch motor in accordance with movements of the gear shifting mechanism, also includes a mechanism for energizing the clutch motor when the speed of'the vehiclehas reached a predetermined low idling speed. Such mechanism is also utilized for controlling the deenergization of the clutch motor through conduit 41, and the construction is such that such deenergization will take place in a manner to secure a finely I graduated and efficient engagement of the clutch,

valve device 49 constructed in a manner similar to that disclosed in the patent of Roy S. Sanford, No. 2,228,612, dated January 14, 1941. More particularly, such valve mechanism includes a housing 50 having inlet, outlet and exhaust chambers 5|, 52 and 53 respectively. A valve 54 having interconnected intake and exhaust portions 55 and 56, respectively positioned in chambers 5| and 52, is provided for controlling the flow of fluid pressure to thevalve device 49. Intake portion 55, when open, establishes communication between chamber 52 and chamber 5|. Valve 56, when open, serves to connect chambers 52 and 53 by way of port 51 and openings 58 formed in a valve operating member 59. The latter is secured to a diaphragm 60 and is capable of longitudinal shifting movement through the action of a suitable centrifugally operable device and connecting chambers 5| and 52. The latter is in constant communication with a conduit 65 which is adapted to be connected to or disconnected from conduit 41.through the operation of a valve mechanism 65 to be referred to more,

engine speed.

Fluid under pressure is conducted tothe inlet chamber 5| from the reservoir 26 through a valve device 10, controlled by movement of the primary shifter rail |1, said valve device being connected with the reservoir by conduits 1| and 21 and with chamber 5|, by way of conduit 69. With the gear shift in the neutral position shown, and assuming valve 66 to be conditioned to establish aconnection between conduits 41 and 65, in a manner to be described more fully hereinafter, fluid pressure conducted to the inlet chamber 5| will be fed to conduit 41 past the open intake valve 55, chamber 52, conduit 95 and valve 56. It will be understood from the construction previously de scribed that conduit 41 communicates with the clutch motor when the gear shift is in neutral. Thus, under these conditions, the valve mechanism 49 will be effective to cause disengagement of the vehicle clutch.

The present construction, in addition to the above, also enables the disengagement of the vehicle clutchby operation of valve mechanism 49 when the gear shifting mechanism is established in either first or reverse gear relations. Under these conditions, fluid pressure is conducted from valve mechanism 49 to the clutch motor in precisely the same manner as that above indicated. However, in the event that second orthird gear relation is established, thus necessitating the movement of the primary shifter bar H, the supply of fluid pressure from conduit 6| drivably connected through a belt 52 to any movable part of the engine which is, proportional to the engine speed. Upon increase of engine speed, mechanism 6| tends to move member 59 to the right against the tension of a spring 63. Thus, upon increase of engine speed,

valve operating member 59 will move away from as to cause member 59 to contact exhaust valve portion 56, thus opening intake valve portion 55 21 to conduit 69 is shut off by valve device 19.

Thils, even though the'engine speed drops suf- M ficiently low as to open the intake valve 55 of valve mechanism 49, still the clutch would not become disengaged. This action results from the use of the valve device 19 which. includes a valve 12, engaged by a spring 13, which, when the shifter bar 11 is in neutral position, is fully extended and permits-the valve 12 to be opened. Spring 13 is carried by a valve operating member 14 which has a cam-shaped extremity 15 adapted to be received within notch 1 5 of the shifter bar l1, see Fig. 3. When the shifter bar H is moved out of neutral, to establish second or third gear duits'89 and, 1| will be. cut off and valve mechanism 49 will not conduct fluid pressure clutch motor.

As has heretofore been stated, certain clutches t9 the utilized in present day practice have a relatively high mechanical friction loss which must be overcome before the clutch springs are compressed to secure disengagement of the clutch. With the clutch disengaged, the force necessary to overcome the mechanical friction loss must be relieved before the clutch starts to reengage. If the centrifugally controlled valvular mechanism 49 disclosed herein were to graduate the release of not only, the force required to overcome friction loss but also the force required to overcome the energy of the clutch return springs, the engagement of the clutch may not be as gradualand smooth as may be desired, especially if the clutch has a high mechanical friction loss compared with the force necessary to actually.

sponding to that required in the clutch motor to hold the relatively movable members of the clutch in very slight engagement. This is accomplished by adjusting member 68 and hence the tension of spring 63. Under these conditions, the valvular mechanism 49 operates as a pressure reducing valve and exhausts all fluid pressure in excess of the amount just indicated.

With the clutch motor 1 supplied with reservoir pressure; which is suflicient to overcome the mechanical friction loss of the clutch and to hold the clutch members fully disengaged," it is desirable, as above stated, to deenergize the clutch motor 1 down to the point where the clutch plates are in slight initial engagement. Preferably, this decrease in deenergization of the clutch motor should be effected rapidly and without any increase in the speed of the engine. For this purpose, valve 66 is provided and is operatively associated with the throttle operating member or accelerator pedal 80 through a bell crank 8!, one end of which is connected to a rod 82. The free end of the latter is provided with a pin 83 positioned within a slot 84 formed in a fitting 85 carried by a throttle control rod 86, the latter being associated with throttle valve 81 of the engine carburetor 88. .A spring 89 duit 41. Under these conditions, fluid pressure from conduit 69 will be conducted to conduit 41 upwardly, as viewed in Fig. 1, and, with the parts in the position shown, urges exhaust valve portion I02 into contact with an exhaust valve seat I03 formed on the lower end of member 93. The latter is provided with an interiorly disposed bore I04 having an opening I05 in constant communication with conduit 65 so that, when exhaust valve I02 is disengaged as respects its seat, conduit 41 is connected with conduit 65 through chamber 99, bore I04 and opening I05. When the accelerator pedal 80 is depressed and pin 83 carried by rod 82 is moved in slot 84, a spring I06 interposed'between casing 96 and a collar I01, carried by member 93, is effective to move the latter upwardly to such a position that arm 9I engages a fixed stop I08. These parts are so constructed and arranged that, when this operation occurs, intake valve 91 closes, exhaust valve I02 is opened, and fluid pressure from the clutch motor is conducted to conduit 41, by the connections heretofore set forth, and from the and from the latterto the clutch motor 1 by way of the connections heretofore set forth, and the pressure in the clutch motor 1 will be substantially equal to that in the supply reservoir 26. A spring IOI constantly tends to urge valve 95 conduit 41 to conduit 65, through the valvular mechanism 66. As soon as this pressure, which is the same as that in the reservoir, is led from conduit 65 to the outlet chamber 52, the'same mosphere by way of valve portion 56, the duct 51, openings 58 and exhaust chamber 53, and this reduction in pressure will continue until the pressure is decreased to the value determined by the initial adjustment of spring 63. As soon as the pressure has been reduced to this amount, the exhaust valve 56 will be closed and no further reduction in the pressure within clutch motor 1 will occur, the valve 54 under these con ditions being lapped. At this stage of the operation, the pressure remaining in the clutch motor 1 is just sufficient to permit light initial engagement of the clutch plates. Further reduction in the energization of the clutch motor in order to secure smooth and gradual engagement of the clutch will take place as the engine speed is increased, through depression of the accelerator pedal, the centrifugally controlled mechanism 6i, under these conditions, serving to move valve operating member 59 to the right, as viewed in Fig. 1, in order to graduate the release of fluid pressure in chamber 52. Thus the centrifugally controlled valvular mechanism 49 will be able to closely and finely graduate the release of pressure from the clutch motor to secure smooth clutch engagement.

A modified form of the invention is disclosed in Fig. 2, and, therein, it will be observed that the transmission 6 and the valves 20, 2! and 12, controlled by movement of the shifter bars I6, I8 and I1, I9, are identical withthose heretofore described in connection with Fig. 1., The only difference between the form of the invention shown in Fig. 1 and the modification illustrated in Fig. 2 is in the arrangement of the .valvular mechanisms for controlling the application and exhaust of fluid pressure to and from the valve devices controlled by the shifter bars.

As shown in Fig.2, the reservoir 26 is adapted to supply fluid pressure to the valve device 10 through a conduit I30, a branch conduit I3I connecting conduit I30 with the casing 25 housing inlet valves 22 and I22. A conduit I32 communicates with the bore 45 of the valve operating member 42, through the slotted portion 46 in said member, the conduit I32 serving to convey and exhaust fluid pressure to and from the clutch motor 1 in a manner which will appear more fully hereinafter.

In this form of the invention, the centrifugally operable valve mechanism 49 of Fig. 1 has been rearranged, and it will be observed that the valve chamber I40 and exhaust chamber I4I, such communication being permitted by ports 42 provided in the side wall of member I38. The member I38 cooperates with an exhaust valve portion I43 of a valve I44, the latter having an inlet portion I45 positioned within an inlet chamber I46. Such inlet chamber communicates with conduit I30 through valve device 10 as by means of conduit I41.

The valve operating member I38 has a casing I48 secured thereto and the valve "operating member and casing together form a riding valve mechanism I49. As shown, the valve mechanism I49 includes exhaust, outlet and inlet chambers I50, I5I and I52, a valve I53 being provided with an inlet portion I54 and an outlet portion I55 serving to control the flow of fluid pressure between the aforesaid chambers. A spring I55 normally tends to move valve I53 to the right, and, in the position shown, the exhaust valve portion I55 engages the left-hand end of a valve operating member I56, said end being provided with a bore I51 and suitable openings I58 which serve to connect chambers I50 and I5I when the exhaust valve portion I 55 is off its seat. Resilient means, such as a spring I59, is interposed between a cap I60 of easing I48 and a collar I6I secured to member I56, said spring being lighter than spring I62 associated with diaphragm I31 and tending to urge the valve operating member I56 toward the left, as viewed in Fig. 2. The latter slidably passes through an adjustable threaded member I63, positioned in cap I60, the

threaded member acting as a stop for collar I6I when the latter moves to the right. Valve operating member I56 is moved to the right, as viewed in Fig. 2, as, by means of a suitable centrifugally operated mechanism I64 drivably connected to any part of the engine which is responsive to the rotational speed thereof.

As has been heretofore stated, in connection with Fig.1, certain types of clutch installations require the application of a relatively considerable force for overcoming the inherent mechanical friction before the applied force-is effective to cause clutch disengagement. In the event that fluid pressure is utilized for disengaging the vehicle clutch, as in the present invention, and sufficient fluid pressure has been utilized to not only overcome the mechanical friction loss but also that necessary to compress the clutch return springs, it is desirable to rapidly exhaust the fluid pressure within the clutch actuating mechanism down to the point where the clutch plates are in light initial engagement and to thereafter graduate the remaining decrease in pressure, as the speed of the engine is increased, in order to permit smooth and gradual clutch engagement. This desirable action is secured by the modification above specifically described in the following manner.

Assuming that the shifter bars I6 and I8 have been moved to establish first gear relation and the engine is idling, full reservoir pressure is present within clutch cylinder 1. The clutch cylinder is in communication with the-reservoir 26 through conduit 23, valve chamber I28, duct 38, bore 4|, chamber 28, duct 45, conduit I32, outlet chamber I5I of valve mechanism I49, intake chamber I52, conduit I65, conduit I41, valve device 10 and conduit I30. If the operator desires to proceed in first gear, the engine speed is increased in the usual manner and the action of the centrifugally operated mechanism or governor I64 tends to move valve operating member I56 toward the right. As this movement occurs, intake valve I54 closes and exhaust valve I55 opens, thus connecting outlet chamber I5I with exhaust chamber I50 and conducting fluid pressure from the clutch motor via the connections above set forth, including conduit I32, to a conduit I66 connecting the exhaust chamber I50 with the outlet chamber I40 of valve mechanism I333. The tension of spring I62 associated with diaphragm I31 is preferably so adjusted as by means of threaded member I61 as to permit the valve mechanism I33 to operate as a pressure limiting valve in the same manner as the valve mechanism 49 heretofore described in connecvalve operating member I56, the spring I58 is taken up and the collar I6I will eventually contact'the adjustable member I63. Such contact will not be effected, however, until the initial exhaust of pressure referred to above has occurred by reason of the pressure limiting action of valve mechanism I33. Upon further increase in engine speed and engagement of collar I6I with member I63 has occurred, the entire casing I48 of valve mechanism I49, together with valve operating member I 38 secured thereto, will be moved to. the right, as viewed in Fig. 2, in order to effect further operation of valve mechanism I33 and achieve graduated exhaust of fluid from conduit I66 connected to the clutch motor by the connections heretofore set forth. It will thus be understood that, during initial increase in the speed of the engine, the pressure in the clutch motor will be suddenly dropped to a value sufficient to hold the clutch in light engagement and that the remaining exhausting of fluid pressure, in order to graduate the engagement of the clutch, will be secured as the motor speed is gradually increased.

In shifting from first to second gear, for example, it will be understood that the shifter bars I6 and I8 are first moved back to neutral. Upon initial movement of these bars out of first gear relation, valve portion I22 will be opened in order to connect the fluid motor 1 with the reservoir 26 by way of conduit 29, chamber I28, casing 25 and conduits I 3| and I30. Reservoir pressure will thereupon be conducted to the clutch actuator in order to secure clutch disengagement prior to disestablishing the first gear relation. As soon as shifter bars l6 and I8 are returned to neutral, shifter bars l1 and I9 are moved to such a position as to establish the second gear relation, and, as soon as this is attained, reengagement of the clutch will take place in the manner heretofore stated. Likewise, in shifting from second to third gear, the clutch will be coordinately disengaged and reengaged inthe manner described above.

There has thus been provided by the present invention two novel arrangements for securing coordinated power operation of the vehicle clutch during shifting movement of the vehicle transmission. The arrangements are such that no special attention or manipulation need be practiced by the operator, it being merely necessary to decelerate the engine prior to shifting and to accelerate the engine after the desired gear relation has been established. Of particular importance are the arrangements provided, wherein efllcient and gradual clutch engagement may be secured'notwithstanding the fact that a substantial force is necessary to overcome the mechanical friction losses in the clutch mechanism.

While two embodiments of the invention have been illustrated and described with considerable particularity, it is to be understood that various modifications may be resorted to without departing from the spirit of the invention, as will be understood by those skilled in the art. Reference will, therefore, be had to the appended claims for a definition of the limits of the invention.

Certain subject matter disclosed herein is claimed in my divisional application Serial No. 394,565, filed May'2l, 1941.

- What is claimed is:

'1. In combination with an automotive vehicle engine, a gear-changing mechanism, and a clutch, of a fiuidpressure operated motor for controlling the disengaging and engaging movements of said clutch, means controlled by operation of said mechanism for energizing said motor to disengage the clutch, and means for controlling the deenergization of said motor to cause to the clutch, and control means for rendering the power device operative to disengage or permit engagement of the clutch, said control means including a portion automatically operative for checking the movement of the clutch as the latsubstantially the point of initial engagement, and means for operating said portion to exhaust the remaining fluid pressure supplied to the motor from said source in accordance with the speed of the engine, whereby controlled engagement of the clutch will be eifected. W

ter reaches substantially the point of initial ensure from said motor until the clutch reaches 4. In an automotive vehicle provided with an internal combustion engine and a clutch, power means for operating the clutch to cause engagement and disengagement thereof, and means for controlling said power means for causing clutchdiseng aging operation thereof including a reservoir, a pair of valves connected in parallel between said reservoir and' power means, and means dependent upon the'speed of said engine for operating said valves in sequence.

5. In an automotive vehicle provided with an internal combustion engine and a clutch, power means for operating the clutch to cause engagement and disengagement thereof, and means for controlling said power means for causing clutchdisengaging operation thereof including a reservoir, a pair of valves connected in parallel between said reservoir and power means, means for adjusting one of said valves for a limited power output, and common means for operating said valves in accordance with the speed of the englne- 6. In an automotive vehicle provided with an internal combustion engine and a clutch, power means for operating the clutch to cause engagement and disengagement thereof, and means for controlling said power means for causing clutchdisengaging operation thereof including a reservoir, a pairof valves connected in parallel between said reservoir and power means, and governor means for operating one valve independently of the other and for thereafter operating said valves in unison.

'7. In combination with an automotive vehicle engine and a clutch, of a fluid pressure motor connected to the clutch, a source of fluid pressure, and means including a pair of control valves for controlling the flow of fluid pressure from -the reservoir to the motor for eifecting clutch disengagement and for controlling the release of fluid pressure from the motor for effecting clutch engagement, one of said valves being automatically operable for limiting the release of fluid pressure from the motor as the clutch reaches substantially the point of initial engagement and for thereafter controlling the move ment of the clutch into and out of operative engagement in accordance with the speed of the engine, and the other valve bgng operable to prevent iimiting of the pressure in the fluid motor by said first named valve and to connect the source of fluid pressure directly with the motor for effecting complete clutch disengagement.

3. In combinationwith an automotive vehicle engine, a'. gear-changing mechanism, and a .clutch, of a fluid pressure-operated motor for controlling the disengaging and engaging movement of said clutch, means controlled by the operation of said mechanism for energizing said motor to disengage the clutch, and means for controlling the deenergization of the motor to effect engaging movement of the clutch including a portion automatically operative for checking the movement of the clutch as the latter reaches substantially the point of initial engagement, and for thereafter controlling the movement of the clutch into and out of operative engagement in accordance with the speed of the en ine. v

9. In combination with an automotive vehicle engine, and a clutch, of a fluid pressure-operated motor for controlling the disengaging and engaging movements of said clutch, means for en'- ergizing said motor to disengage the clutch, and means for controlling the deenergization of said motor to cause clutch engagement comprising a. pair of interconnected valves, means for adjust- 

